1. Technical Field
The present invention relates to a bearing installed between two Micro Electro Mechanical System (MEMS) structures performing a relative movement and configured to perform a rolling movement and, more particularly, to a roller bearing having a tolerance compensation function, which is capable of being properly deformed and absorbing a processing tolerance within a range of an elastic region even when a distance between MEMS structures is changed due to the processing tolerance of the MEMS structures, being deformed to a minimum and rolled while maintaining a smooth contact with the MEMS structures by uniformly dispersing vertical loads applied from the MEMS structures through a plurality of the bearings, and thus minimizing the occurrence of abrasion and preventing damage to the bearing, and a method of manufacturing the same.
2. Description of the Related Art
Recently, researches into damage and abrasion phenomena in micro/nano scale have been further developed in attempts to check the origin of the abrasion phenomenon in the existing macro scale and thus have been presented as essential researches for the practical use of various micro/nano systems which are emerging worldwide.
In reality, the practicality of lots of micro systems performing a relative movement, including MEMS (Micro Electro Mechanical Systems) parts, is limited due to reliability and durability problems, and this phenomenon also appears in nano fields, such as Probe-Based Recording (PBR) technology and Scanning Probe Lithography (SPL) technology.
Since a lubricant or a bearing has not been developed to the extent that the lubricant or bearing can be successfully applied to lots of micro systems including MEMS parts of a micro/nano scale for performing a relative movement, researches into a clear examination on damage and abrasion phenomena occurring in the relative movement process of the MEMS parts of a micro/nano scale and the improvement of reliability and durability are being performed in various manners.
Meanwhile, in some researches, researches into a clear examination on a rolling phenomenon that occurs in MEMS parts performing a relative movement using a micro bearing having a diameter of several tends to several hundreds of μm are in progress. For example, in a prior art thesis issued in ‘Tribology International’ in 2010 (Sujeet K. Sinha, Robin Pang, Xiaosong Tang, “Application of micro-ball bearing on Si for high rolling life-cycle”, Tribology International 43 (2010) 178-187), in order to solve friction and abrasion problems occurring in a relative movement between MEMS structures made of silicon, there was an attempt to obtain a very low friction coefficient of 0.005 to 0.008 by installing a borosilicate glass micro sphere having a diameter of 53±3.7 μm between the MEMS structures performing a relative movement.
However, an image of the glass micro sphere used as a micro ball bearing disclosed in the prior thesis showed that abrasion, sintering deformation, and crack phenomena were generated on a surface of the glass micro sphere. This is because the size of the glass micro spheres is not regular, a surface of the MEMS structure is not perfect flat, and there is a difference in the height of several hundreds of nm between the MEMS structures. As a result, as can be seen from a cross-sectional view of FIG. 1 that is shown in a two-dimensional manner, although several hundreds of glass micro spheres 10 are scattered between MEMS structures 20 and 30 as micro ball bearings, only some of several hundreds of the ball bearings 10 that are first scattered come in point-contact with the MEMS structures 20 and 30, but the remaining ball bearings come in contact with a surface 32 of the MEMS structure 30 on the lower side, but do not contact with a surface 22 of the MEMS structures 20 on the upper side.
In this case, a vertical load is not distributed, but is concentrated on only some of several hundreds of the ball bearings 10 because the ball bearings 10 scattered between the two MEMS structures 20 and 30 come in contact with the two MEMS structures 20 and 30 at once as described above. Accordingly, a sintering deformation is generated in some of the ball bearings on which the vertical load has been concentrated, and the ball bearing is deformed in an elliptical form not a circular form. In this case, the shape of the sintered and deformed ball is not restored to its original shape and thus a smooth rolling phenomenon is not performed. As a result, there are problems in that the ball bearing is severely abraded although the deformed ball is forcibly rolled and thus the ball bearing is broken. Furthermore, if a sintering deformation occurs only in some of the ball bearings, there are problems in that the micro balls are deformed until the number of balls capable of withstanding the vertical load comes in contact with the MEMS structures and the remaining micro balls do not function as rolling bearings properly because they do not come in contact with the surfaces of the MEMS structures.